Heat exchanger



R. M GANN HEAT EXCHANGER Nov. 11, 1969 5 Sheets-Sheet 1 Filed July 15, 1967 rllll INVENT OR RODNEY M GANN ATTORNEY R. M GANN HEAT EXCHANGER Nov. 11, 1969 5 Sheets-Sheet 2 Filed July 13, 1967 v INVENTOR RODNEY MGANN m m/fi ATTORNEY R. M GA-NN HEAT EXCHANGER Nov. 11, 1969 5 Sheets-Sheet 5 Filed July 15, 1967 INVENTOR RODNEY M GANN ATTORNEY R. M GANN HEAT EXCHANGER Nov. 1 1, 1969 5 Sheets-Sheet 4 Filed July 13, 1967 fiLfII2II) INVENTOR RODNEY M GANN BY M ATTORNEY R M GA N N HEAT EXCHANGER Nov. 11,- 1969 5 Sheets-Sheet 5 Filed July 13, 1967 INVENTOR RODNEY MGANN ATTORNEY United States Patent 3,477,505 HEAT EXCHANGER Rodney McGann, Northridge, Calif., assignor, by mesne assignments, to Texaco Inc., New York, N.Y., a corporation of Delaware Continuation-impart of application Ser. No. 346,197,

Feb. 20, 1964. This application July 13, 1967, Ser.

Int. Cl. F28d 7/02; F02k 3/00, 11/00 US. Cl. 165-164 4 Claims ABSTRACT OF THE DISCLOSURE Heat exchangers of particular utility in air breathing reaction engines comprise a bundle of substantially parallel pipes, input header means supplying fluid to one end of the pipes in the bundle and outlet header means withdrawing fluid from the other end of the pipes, the lengths of the pipes and their longitudinal positions in the bundle being such that the inlet and outlet headers lie in the nonplanar Surfaces or in planar surfaces oriented at angles of less than 90 with the longitudinal axes of the pipes in the bundle and the dimensions of the headers being such that the maximum total transverse area of the headers in any transverse plane therethrough does not exceed the maximum total transverse area of the pipes in any transverse plane through the bundle. The surfaces defined by the inlet and outlet headers may be curvilinear or planar.

This application is a continuation-in-part of application Ser. No. 346,197, filed Feb. 20, 1964.

This invention relates to improvements in heat exchangers and, in particular, to an improved heat exchanger for use in air breathing reaction engines of the type wherein a portion of the energy of the ram air is transferred to the fuel by heat exchange between the ram air and the fuel.

It had been found that by locating a heat exchanger in the air inlet of air breathing reaction engines, the heat exchanger will cool the ingested diffused air so that the engine downstream of the heat exchange will not be subjected to temperatures exceeding, for example, that corresponding to about Mach 3 (about 650 F.) during Mach 8 flight conditions and the air stream having passed the heat exchanger is more easily compressed.

It is, therefore, a principal object of the invention to provide a single pass, counterflow, high temperature air cooling heat exchanger having generally low Weight and low frontal area with a minimum of pressure loss.

These and other objects and advantages are provided in a heat exchanger including a bundle of substantially parallel pipes, input header means supplying fluid to one end of the pipes in the bundle and outlet header means withdrawing fluid from the other end of the pipes, the lengths of the pipes and their longitudinal positions in the bundle being such that the inlet and outlet headers lie in nonplanar surfaces or in planar surfaces oriented at angles of less than 90 with the longitudinal axes of the pipes in the bundle and the dimensions of the headers being such that the maximum total transverse area of the headers in any transverse plane therethrough does not exceed the maximum total transverse area of the pipes in any transverse plane through the bundle.

The invention will be more fully described in reference to the illustrative embodiments thereof shown in the accompanying drawings wherein:

FIG. 1 is a generally diagrammatic view in partial transverse cross-section of an air breathing reaction propulsion engine employing a ram air heat exchanger constructed in accordance with the teachings of the present invention;

FIG. 2 is a front end view of the heat exchanger of FIG. 1;

FIG. 3 is a median longitudinal section through the heat exchanger of FIG. 2;

FIG. 4 is a front end view of another form of the heat exchanger of the invention, wherein the header members are of general circular shape rather than spiral as in the exchanger of FIGS. 1-3;

FIG. 5 is an enlarged partial longitudinal section in line 5-5 of the heat exchanger of FIG. 4;

FIG. 6 is a front end view of a further form of the invention in which the heat exchanger is generally rectangular in transverse section and the header members terminate in a dihedral surface; and

FIG. 7 is a transverse section of line 7-7 of FIG. 6.

Referring to the drawings and, in particular, to FIG. 1, 10 generally designates an air breathing reaction engineof the type wherein a portion of the energy of the ram air entering the forward end of the engine is transferred to the fuel by heat exchange between the ram air and the fuel as disclosed and claimed in, for example, application Ser. No. 324,957, R. L. Wolf and Rodney McGann, Reaction Propulsion Engine and Method of Operation, filed Nov. 20, 1963, and assigned to applicants assignee.

In general, the reaction engine 10 includes a shell 12 having a forward end 14 and a rearward end 16. The forward end 14 of the shell or casing 12 connects to the inlet duct for ram air, the path of the ram air being indicated by the directional arrows A. In the forward end 14 of the ram air passage is the indirect heat exchange means 18 of the invention. The heat exchange means 18 has the outer surface of the heat exchange elements thereof in contact with the ram air entering the engine while the interior of the indirect heat exchange means provides a path for the flow of fuel from the fuel tank 20.

Fuel from the fuel tank 20 is directed by pump 24 through a conduit 22, thence through conduit 26 to a main rear header 28. Fuel, after passing through the heat exchanger 18, is directed therefrom via forward main header means 30, thence through conduit 32 to a fuel flow regulating mechanism generally designated 34. From the fuel flow regulating mechanism 341 a portion of the fuel is directed to the turbine 36 and a portion of the fuel may be directed to a regenerative heat exchanger 38 positioned in the combustion chamber 40 for the reaction engine and/or a portion may be directly expanded into the combustion chamber via conduit 42. The turbine 36 drives a compressor 44 which compressor compresses air entering the ram air inlet 14 after the air has been cooled in its passage through the heat exchange means 18. The products of combustion of the fuel and the compressed air and any excess fuel or excess air issue from the nozzled outlet 16 of the reaction engine.

Referring now to FIGS. 1 through .3, in the heat exchange means 18 in the illustrated form of the invention, the rear header means 28 is connected to the forward header means 30 by a bundle 50 of heat exchange pipes 52. The rearward ends of each of the pipes 52 may be constructed of aluminum, the forward portions of the pipes may be constructed of, of example, columbium, while the intermediate sections may be constructed of steel. Thus, the single pass counterflow arrangement of the heat exchange tubes permits the use of less exotic materials in the rear or cooler part of the heat exchanger thereby not only reducing the Weight of the assembly but also the cost of materials of construction.

The bundle of heat exchange pipes 50 is connected to the rearward header means 28 through a plurality of secondary header pipes 60. Each of the header pipes 60 has one end in fluid communication with the primary header 28 and each of the secondary header pipes 60 spirals generally inwardly and forwardly. The most inner and forward end of each of the secondary header pipes 60 is closed and each of the secondary headers 60 controls the flow of fluid to a plurality of the heat exchange pipes 52 of the bundle of pipes 50. Interconnecting a plurality of the heat exchange tubes 52 to the generally spiral secondary header pipes 60 has the particular advantage that thermal expansion of the headers will bring about rotation of the segments rather than primarily radial growth, thereby keeping to a minimum the necessity for expansion joints and fl1e like in the system. A similar arrangement of secondary generally spirally arranged forward headers 62 connects the forward ends of the heat exchange pipes 52 of the bundle of pipes 50 to the forward primary header 30.

In the embodiment of the invention shown in FIGS. 4 and 5, the secondary headers 70 and 72 are circular ducts arrayed in a conical surface by means of pipes 74a, 74b and 740 and 76d, 76b and 760 connecting the inlet and outlet headers 28 and 30 with adjacent pairs of circular ducts 70, 72 respectively.

The embodiment of the invention shown in FIGS. 6 and 7 is particularly adapted for use in passages of rectangular transverse section. In this embodiment rectangular inlet and outlet headers 78 and 80 supply and withdraw fluid from sets of secondary headers 82, 84 respectively. Secondary headers 82, 84 are connected by parallel pipes 86 the ends of which define parallel congruent dihedral surfaces.

The secondary headers may be curvilinear in shape whereby the ends of the parallel pipes define hemicyclindrical or other curvilinear surfaces.

In order to provide substantially equal heat transfer areas across the transverse section of the heat exchanger the heat exchange pipes 52 and 72 of FIGS. 1 and should preferably be distributed in proportion to the cross-sectional area of each portion of the pipe bundle to maintain a substantially uniform area of the pipes in each unit area heat exchanger duct as indicated in the drawings.

As illustrated in FIG. 1 of the drawings, the forward primary header 30 is connected to conduit 32 through a slip joint or flexible connector 66; therefore, all axial expansion is taken up in the single joint. It will be appreciated that the forward primary header 30 may be rigidly attached to the vehicle and the rearward primary header 28 may be connected to the conduit 26 through a suitable expansion joint whereby axial expansion would only be in the rearward direction toward the compressor 44 or each header may be connected to its respective pipe by a suitable heat expansion joint (not shown). Further, the heat exchanger of the present invention may be readily tailored for a particular reaction engine or vehicle mission by increasing or decreasing the axial length of the heat exchanger assembly without changing the fundamental design parameters of the device.

It will be noted that the shape of the non-planar surfaces defined by the ends of the heat transfer pipe bundles may be curvilinear, for example, spheroidal, parabaloidal, allipsoidal, or conical or they may be planar or polyhedral, for example, dihedral or tetrahedral. Preferably, the surfaces defined by the inlet and outlet ends of the pipe bundles are congruent.

I claim:

1. In an air breathing reaction engine having a shell provided. with an open forward heat exchanger receiving end portion, a heat exchanger operatively mounted in the forward heat exchanger receiving end portion, said heat exchanger comprising a bundle of substantially parallel pipes arranged axially within the forward end portion and having opposing ends, inlet header means supplying fluid to one end of each of the pipes in the bundle, said inlet header means including a main inlet header and secondary inlet headers connecting the main inlet header to the one end of each of the pipes in the bundle, outlet header means withdrawing fluid from the other end of each of the pipes in the bundle, said outlet header including a main outlet header and secondary outlet headers connecting the main outlet header of the outlet header means to the other end of each of the pipes in the bundle, the lengths of said pipes and their relative positions lengthwise of said bundle being such that the inlet and outlet header means lie in non-planar surfaces or in planar surfaces oriented at angles of less than 90 with the longitudinal axes of the pipes in the bundle and the dimensions of the inlet and outlet header means being such that the maximum total transverse area thereof in any transverse plane therethrough does not exceed the maximum total transverse area of the pipes in any transverse plane through the bundle.

2. The invention of claim 1 wherein at least one of the surfaces defined by the inlet and outlet header means is curvilinear.

3. The invention of claim 1 wherein at least one of the surfaces defined by the inlet and outlet header means is polyhedral.

4; The invention of claim 1 wherein the pipes in the bundle are equal in length and the surfaces defined by the inlet and outlet header means are congruent.

7 References Cited UNITED STATES PATENTS 3,130,779 4/1964 Huet 16s- 163 3,379,244 4/1968 Gilli 165163 2,483,045 9/1949 Harby 60-267 2,798,361 7/1957 Hiersch 60 267 x 2,990,162 6/1961 Otten 165-153 FOREIGN PATENTS 683,267 11/1939 Germany.

ROBERT A. OLEARY, Primary Examiner T. W. STREULE, Assistant Examiner US. Cl. X.R. 60-246, 267, 269 v v 

